Electromagnetically operated pendulum type telegraph key



Patented Aug. 12, 1947 UNITED STATES PATENT OFFICE ELECTROMAGNETICALLY OPERATED PEN- DULUM TYPE TELEGRAPH KEY Bernard H. Breedlove, San Mateo, Calif.

Application August 6, 1945, Serial No. 609.282

8 Claims. 1

My invention relates to a telegraph key and particularly to a semi-automatic radio telegraph key.

One of the objects of the invention is the provision of a key with which the telegraph operators speed may be materially increased With no added effort. Another object is the provision of means for the automatic production of dot impulses in an unbroken train and which is instantly responsive to a manual control key. Another object is the provision in a semi-automatic device of the character described in which the dots are automatically repeated under instant control and the dashes are manually effected, of means foradjusting the dot length to suit the operators speed of sending, so that the dots may be th preferred length of one-third the dash length.

The invention possesses other valuable features. some of which with the foregoing will be set forth at length in the following description Where that form of the invention which has been selected for illustration in the drawings accompanying and forming a part of the present specification is explained. In said drawings, one form of. the invention is shown, but it is to be understood that it is not limited to that form, since the invention as set forth in the claims may b embodied in a plurality of forms.

The figure of the drawings is a diagrammatical view of the apparatus and circuits of my invention.

With a manually operated telegraph key, a good operator may attain a speed in Morse code of perhaps thirty words per minute, although the average with a hand key is probably less than twenty. Constant manual operation of the key sometimes causes a serious condition in the operators muscular control of arm and hand, so that sending may be not only slowed up, but irregularity in the dots and dashes introduced which affects the clarity and accuracy of the transmitted message.

Besides an always Worth while increase in sending speed, it therefore becomes desirable to relieve the operator as much as possible of the physical burden of sending and to substitute for the variable, manuall produced dot impulses, manually controlled but electro-mechanically produced ones of perfect regularity in length and spacing, leaving the dashes to be separately initiated by slight manual movement.

In broadly descriptive terms I accomplish this by providing a magnetically operated impulse actuator, the operation of which, after being started by the operator, opens and closes an electric circuit to produce the familiar dot of the Morse code in a continuous train or series of dots, but more evenly and faster than digital manipulation of the key could efiect. A pendulum weighted for adjustment of its swing is arranged to be vibrated by an electro-magnet so that it closes and opens alternately a telegraph circuit, which may be a circuit controlling a radio transmitter. The magnet is energized through two different circuits. One, supplying the heavier current, is normall closed to hold the pendulum in inactive position. The other which supplies a much lighter current comes into automatic operation with the opening of the first circuit by the hand of the operator when he starts sending. Actuated by th second or dot initiating circuit so long as the first circuit remains open, the vibrating pendulum first closes and then opens the radio transmitter circuit at regular and even intervals until the first circuit is again closed by the hand of the operator for the interposition of a dash, as required by the code.

In order to preserve throughout the apparatus th desirable features of a closed circuit system, the dash impulses are supplied through the oper ation of a relay connected in parallel with the first or main circuit of the electro-magnet.

In terms of greater detail, the apparatus of my invention comprises an electro-magnet 2, the core 3 of which is arranged to attract the armature 4, conveniently forming the head of the pendulum 6. pendant from the bracket 1 by means of the fiat spring 8, fixedly supported on the bracket, so that the pendulum may vibrate back and forth because of the resilience of the spring, and in response to the magnetic field when the magnet coils are energized.

A Weight 9 is adjustably mounted on the pendulum so that the speed of its response to the spring and magnet may be adjustably varied. This adjustment is primarily to vary the number of dots per unit of time. An adjustable stop I2 is also preferably provided to avoid whip in the pendulum by engaging the end of the pendulum on the magnet attracted stroke. This stop fixes the position of the pendulum when the circuit through the magnet is closed and the pendulum is inactive.

The circuit for energizing the electro-magnet 2 to hold the pendulum in inactive position com prises the conductors l3l4l5 and key IE, through contacts I! to conductors l8-l9g and the magnetic field energized by this current strongly attracts the armature and retains it against the core. While this is necessary to secure the pendulum in its inactive position, it is desired to use a succession of weaker fields in cooperation with the pendulum spring to cause an even vibration of the pendulum to initiate the dot impulses. This is done by providing a second circuit fo the electro-magnet through conductors l3l4--2I, contacts 22, variable resistance 23 and conductors 24--I 9. One of the contact points 22 is arranged on a spring arm 26 fixed to vibrate with the pendulum and conveniently mounted on the head 4 thereof; and the other is mounted for adjustment by means of the screw 21, to which the variable resistance 23 is connected.

It will be seen that if the keyed circuit through the contacts I! be broken, the pendulum will be released from the position in which the drawing shows it; and the spring 8 in aid of gravity will start a swing which will continue through its full amplitude so as to engage the contacts 22, closing the resistance-modified circuit through the magnet. To the spring and gravity is then added the lightened pull of the core 3. These forces cause the pendulum to swing back, breaking the circuit through the magnet, but swinging through full amplitude because of momentum of the swinging parts. The strength of current in this second circuit is materially less than that through the key contacts l1; and need be only sufiicient to give the pendulum a slight momentary pull. This result is readily attained as a result of cutting in the variable resistance 23. The pendulum now lies in first position but with no magnetic field to hold it; and the flexed spring and gravity start it again toward the right and engagement of the contacts 22, closing the circuit through the magnet, and giving it just enough new impulse to start a new cycle of swings over to left (of figure) and then back again to right. This would continue indefinitely if the key contacts I! remained open. Closing these contacts establishes the full current through the magnet 2; and the pendulum is pulled over and held in the inactive position shown in the figure.

What has just been explained is utilized by me to key a signal transmitting circuit such for example as one to a radio telegraph transmitter. I do this by mounting a second spring arm 3| to move with the pendulum, and arranging contacts 32, one on the arm and the other on the adjustable screw 33. The contacts 32 form the terminals of the radio transmitter circuit 34; and the adjustments are such that on each swing of the pendulum, as described, to engage the contacts 22, the contacts 32 are also engaged to close the radio transmitter circuit and transmit a dot. So long as the circuit through the key contacts I! is open, a train or sequence of uniform dots will be automatically transmitted, the train ceasing instantly upon allowing the circuit through the contacts I! to close. It will be apparent that by turning the screw 33, the duration of the period of engagement of the contacts 32 may be varied over a considerable range. This adjustment is utilized in the initial set up of the mechanism, and subsequent adjustment in dot length are made by varying the resistance in the second circuit.

By adjustment of the variable resistance 23, the period during which the radio transmitter circuit is closed, and hence the length of the dot may be altered into desired relationship with the dash of the operator, without getting out of the range of adjustment of current strength first mentioned which is not critical. It therefore becomes possible to vary the length of the dot to the desired relationship of /3 the dash length, it being understood that the dash, being sent by hand, is more or less characteristic of the sender and less subject to alteration to a fixed pattern.

Means are provided for initiating an impulse resulting in a dash, and supplying that impulse to the radio transmitter circuit. In order to keep a closed circuit system throughout, this is preferably accomplished through a relay. An electromagnet 36 is energized by the circuit-comprising conductors 3'l38, contact points 39, key 4| and conductors 42I9. With the contacts 39 normally engaged, the magnet 35 holds the spring pressed armature 43 against its core, keeping contact points 44 from engagement. One of these points is on the armature 43, and the other mounted for adjustment by means of screw 46. These contacts are connected to the radio transmitter circuit 34, in parallel with the contact points 32 by conductors 41. Opening the circuit through the relay magnet by separating contacts 39, releases the spring held armature 43 to engage the contacts 44, thus closing the radio transmitter circuit through conductors 41 to give a dash impulse in that circuit.

Means are provided for utilizing the devices above explained, so that the dot and dash impulses may be combined and utilized to send or transmit a practicable telegraph code. The lower portion of the drawing figure shows in plan such a code formulating or sending instrument. This instrument as shown comprises two keys arranged close together for operation by the thumb and forefinger of the right hand. Only a light or feather touch is required to move the keys a small amount to initiate the impulses resulting in the dot and dash signals of the radio transmitter; and because of this, a very high speed with a minimum of effort is attained by the skilled operator.

Mounted on a metallic lug 5| fixed on the insulating panel 52 by a screw 53, and for pivotal movement in a vertical axis is a key l6, furnished with one of the contact points H. The associated contact is on the end of the screw 54, threaded in the panel and connected to the conductor l8. Means for limiting the movement or throw of the key I6 is provided by the adjustable screw 56 carried by the bracket 51 fixed in the panel.

The key is operated by means of an electrically non-conducting arm 58 extending therefrom and ending in a handle plate or paddle 59 which provides a convenient engagement for the thumb of the operator. This key is used to initiate the automatically produced train of impulses resulting in the transmission of dots.

Back to back with the key assembly just explained is a second and similar key assembly for initiating the impulses resulting in the transmission of dashes. This assembly including key 4| and paddle 6 l, is the same as that just explained, except that it is in reverse; and will be understood without separate detailed description. The paddle 6| provides a convenient engagement for the fore-finger of the operator, and therefore is spaced from the paddle 59 a distance corresponding to an easy and convenient spread of thumb and finger.

Spring means is provided to insure that the contact points I! and 39 respectively are normally engaged, and to assist the operator in his manipulation of the keys. Preferably such means comprises a conical coil spring 62, interposed between the two key operating arms. The base of the spring is seated on one of the arms and its small end is seated against a screw 63, threaded in the other arm, so that the tension of the spring can be adjusted.

Since the radio transmitter circuit 34 would be closed through the contacts 32, if there is no current through the magnet 2, it is desirable to insert a single throw double pole switch 66 in the radio transmitter circuit and in the first energizing circuit of magnet 2, so that these circuits are under simultaneous control and may be broken during periods of disuse of the key.

The responsiveness of my key cannot be overestimated and is of prime value in the great increase in sending speed possible with it. Opening the key contacts by the merest touch, or less, as limited by the adjusting screw, starts the production of a code dot. One dot only may be sent, or the operator by merely holding the key contacts open by the tightest of pressure on the paddle, may allow the production of a train of evenly spaced, even length dots for an indefinite period. The automatic production and spacing of the dot impulses is instantly interrupted by the release of the key, and the engagement of the key contacts to condition the circuits for the manual or digital production of one or more dash impulses. Releasing the dash key again conditions the system for the use of the dot key. The arrangement of the keys to operate almost as one between the thumb and forefinger; and the very light touch required to operate them, permits sending at speeds of 30 to 50 words per minute with a minimum of strain and eifort, and marked reduction in operators fatigue.

It is also to be noted that because the initiating electrical impulse is stronger and more uniform than. that obtainable loy hand keying, much heavier dots can be obtained, and these can be regulated as to length within a desirable range by adjustment of the variable resistance. This means that my system makes possible a front of panel adjustment of the key to any commercial radio telegraph keying relay, most of which have some time lag which is apt to make a dot sent heavy, actually sound short at the receiving end. This is important on aircraft where the relays are necessarily of heavy design.

I claim:

1. An impulse actuator comprising a pendulum including an armature, a magnet for pulling the armature to move the pendulum to one side of its swing, a key controlled electric circuit for energizing the magnet, a second circuit for energizing the magnet and including contact points operatively connected to the pendulum and separated to open the circuit when the pendulum is pulled to one side of its swing by the armature and engaged to close the circuit when the pendulum moves to the opposite side of its swing, and a variable resistance in the second circuit.

2. An impulse actuator comprising a pendulum including an armature, a magnet for pulling the armature to move the pendulum to one side of its swing, a key controlled electric circuit for energizing the magnet, a second circuit for energizing the magnet and including contact points operatively connected to the pendulum and separated to open the circuit when the pendulum is pulled to one side of its swing by th armature and engaged to close the circuit when the pendulum moves to the opposite side of its swing, a variable resistance in the second circuit, and means for varying the center of gravity of the pendulum.

3. A telegraph key and system comprising a pendulum including an armature, a magnet for pulling the armature to move the pendulum to one side of its swing, a key controlled electric circuit for energizing the magnet, a second circuit for energizing the magnet and including contact points operatively connected to the pendulum and separated to open the circuit when the pendulum is pulled to one side of its swing by the armature and engaged to close the circuit when the pendulum moves to the opposite side of its swing, a variable resistance in the second circuit, and a signal transmitting circuit includ ing contact points operatively connected to the pendulum and separated to open the circuit when the pendulum is pulled to one side of its swing by the armature and engaged to close the circuit when the pendulum moves to the opposite side of its swing.

i. A telegraph key and system comprising a pendulum including an armature, a magnet for pulling the armature to move the pendulum to one side of its swing, a key controlled electric circuit for energizing the magnet, a second circuit for energizing the magnet and including contact points operatively connected to the pendulum and separated to open the circuit when the pendulum is pulled to one side of its swing by the armature and engaged to close the circuit when the pendulum moves to the opposite side of its swing, a signal transmitting circuit including contact points operatively connected to the pendulum and separated to open the circuit when the pendulum is pulled to one side of its swing by the armature and engaged to close the circuit when the pendulum moves to the opposite side of the swing, and means for varying the resistance in the second circuit to vary the duration of the signal.

5. An impulse actuator comprising a pendulum, a contact point on the pendulum, a contact point adjacent the pendulum contact point and with which it engages when the pendulum swings to one side, electro-magnetic means for pulling the pendulum to the opposite side, a normally closed circuit for energizing the electro-magnetic means to hold the pendulum on said opposite side, a key for opening said circuit to release the pendulum to swing to engage said contacts, a circuit including said contacts for energizing the electro-magnetic means, and a variable resistance in the last named circuit.

6. An impulse actuator comprising a pendulum, a contact point on the pendulum, a contact point adjacent the pendulum contact point and with which it engages when th pendulum swings to one side, electro-magnetic means for pulling the pendulum to the opposite side, a normally closed circuit for energizing the electro-magnetic means to hold the pendulum on said opposite side, a key for opening said circuit to release the pendulum to swing to engage said contacts, a circuit including said contacts for energizing the electromagnetic means, a variable resistance in the last named circuit, a signal circuit, and means operated by the pendulum for intermittently closing and opening the signal circuit.

'7. An impulse actuator comprising a pendulum, a contact point on the pendulum, a contact point adjacent the pendulum contact point and with which it engages when the pendulum swings to one side, electro-magnetic means for pulling the pendulum to the opposite side, a normally closed circuit for energizing the electro-magnetic means to hold the pendulum on said opposite side, a key for opening said circuit to release the pendulum to swing to engage said contacts, a circuit including said contacts for energizing the electromagnetic means, a variable resistance in the last named circuit, a signal circuit, means operated by the pendulum for intermittently closing and opening the signal circuit, a second key, and means controlled by the second key for closing and opening the signal circuit.

8. An impulse actuator comprising a pendulum, a contact point on the pendulum, a contact point adjacent the pendulum contact point and with which it engages when the pendulum swings to one side, electro-magnetic means for pulling the pendulum to the opposite side, a normally closed circuit for energizing the eiectro-magnetic means to hold the pendulum on said opposite side, a key for opening said circuit to release the pendulurn to swing to engage said contacts, a circuit including said contact for energizing the electro-magnetic means, a variable resistance in REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,148,028 Martin Feb. 21, 1938 1,036,443 Buquoi Aug. 20, 1912 

